For the choices given:
really depends on the terrain, owners care for the body shine, free of dents/scratches
but for me,
1 - diff covers (can get on sale for the matching pair for under $150, newer jeeps rotate r&p all the time)
2 - gas tank protection (I doubled the thickness on mine for $20 and a little welding)
3 - rocker skids (just had to install mine to fix the body mounts that rusted away, didn't care about the dents/scratches)
Add
4 - steering box protection (I wheel in rocky areas)
5 - bumpers (I wheel in rocky areas that have tall rocks)
6 - self-recovery items (frame mounted winch points, winch)
And this is just for some items but there is a long list of safety requirements/items